Many consumer goods are provided in sealed packages such as heat-sealed polymeric bags. When the packaged goods are perishable goods such as cereal, crackers, or other foodstuffs, it is important that the package be properly sealed to keep the goods fresh and to avoid spillage and contamination of the goods. One type of sealing device used to seal polymeric bags utilizes one or more heater blocks provided on a rotating belt. The blocks cooperate with an adjustable press plate whereby the open end of a polymeric bag positioned between the press plate and rotating belt is sealed as a heater block passes the plate. Advantageously, the speed of the belt and the spacing of the blocks on the belt can be set to correspond to the timing of filled bags provided to a sealing station including the press plate and heater blocks such that continuous sealing of bags in a production line may be accomplished.
One drawback of this type of bag sealing system is that many improperly sealed bags may pass through the sealing station without detection when one or more of the heater blocks fail. The improperly sealed bags must either be reworked or the product in the improperly sealed bags disposed of. In either case, the inability to detect failed heater blocks results in waste and increased manufacturing costs. In the worst case, the improperly sealed bags may pass through the manufacturing system undetected, ultimately resulting in unsatisfied customers.
There is thus a need for an apparatus and method for monitoring the operation of a heat sealing device so that failure of one or more of the heating elements may be detected.